Process of recovering values from smelter-gases.



PATEVNTED B13058, 1903.

R. BAGGALEY. PROCESS OF RECOVERING VALUES FROM SMELTER GASES.

APPLICATION FILED SEPT. 23, 1903.

H0 MODEL.

mvENToR QW 1% a? LIES,

UNITED STATES).

Patented December 8, 1903.

PATENT OFFICE.

RALPH BAGGALEY, OF PITTSBURG, PENNSYLVANIA.-

PROCESS OF RECOVERING VALUES FROM SMELTER-GASES.

SPECIFICATION forming part of Letters Patent No. 746,259, dated December8, 1903.

Application filed September 23, 1903. Serial No- 174379. (No specimens.)

To all whom it may concern.- Be it known that I, RALPH BAGGALEY, ofPittsburg, Allegheny county, Pennsylvania,

have invented a new and useful Process of Recovering Values fromSmelter- Gases, of which the following is a full, clear, and exactdescription, reference being had to the accompanying drawing, formingpart of this specification, which shows in vertical longitudinal'section apparatus suitable for the practice of my invention. I

In smelting ores, such as ores of copper, the dust which is carried fromthe furnace by the smelter-gases often contains'a considerableproportion of metallic values; but the methods heretofore proposed forrecovering and briqueting them for resmelting have been lacking inefiiciency. My invention provides a simple and effective mode ofrecovering such flue-dust and in addition thereto of purifying thesmelter-gas from the noxious elementssulfur, arsenic, &c.--whichheretofore have produced destructive effects upon the vegetationsurrounding the smelter plant. For this purpose I pass the smelter-gasesthrough a chamber containing in one or more compart- .ments or portionsthereof filtering material consisting of matte, converter-slag, or otherproduct of the smelting or refining processes containing metallic valuesdemanding retreatment, or I may use for the same purpose The surface ofthis material is wet with wav-ter sprayed upon it from suitable nozzles,and the material is preferably kept in motion, either intermittent orcontinuous, so that fresh surfaces will be exposed to the gases. Thesegases are in a highly-heated condition when they come into contact withthe material and deposit the flue-dust upon the surface'of the materialin the form of an adherent crust, and when the material is finallyremoved from the chamber-it contains not only the metallic values whichit originally possessed, but the added values of the incrustedflue-dust, and thus enriched it is delivered to the smeltingfurnace orreverberatory furnace for smelting and recovery of the metals therefrom.

In order that the filtering material may be utilized as efficiently aspossible, I prefer to repass it through the chamber one or more times,and at each passage the layer of fluedust thereon is increased inamount.

After the gases have passed through .the value-bearing filteringmaterial I may cause them to pass through other filtering material,preferably through a body or bodies of cracked slag, moistened withwater or with an alkaline solution by which the noxious sulfur fumes orsulfur and arsenic fumesare arrested.

In the drawing, in which I show what I regard as the preferable form ofapparatus for practicing the invention, 2. is a chamber set at thedowntake end of the smelting-furnace and sufliciently close thereto toadmit ofthe gases and flue-dust being received in a very hot state. Inthis chamber is a succession of screen's,each supported, preferably, byaseries of tile steps 3 3', spaced far enough apart to permit the readypassage between them of I the fumes from" the furnace in their flight tothe stack and inclined, preferably, at an angle of about forty-fivedegrees. The first of the screens is composed of pieces of matte, richconverterslag, ore, or other like material containing values fit forsmelting, and the succeeding screens are preferably composed of brokenfurnace-slag, broken stone, gravel,

water-worn boulders, or like material not con taining such metallicvalues.

On top of the fluechamber and immediately above the top step of eachseries is a hopper 4,- arranged to feed the broken filtering material 5,so that itwill flow readily by gravity over the steps in an unbrokenlayer from one side wall to the other anddow'n to the bottom .of theflue-chamber, at which point is a suitable hopper 6, so designed thatvator preferably delivers the fouled material into railroad-cars or intowagons for removal. As the screw conveyers below the chamber are movedslowly by machinery the screen material Will be removed gradually from.the bottom hopper, and the screen material above thus losing its supportwill move downward over the tile steps and ultimately into the lowerhopper, whence it in turn will be expelled by the screw conveyer. As thematerial thus slides down the steps new material 1 constantly entersfrom the hopper above, and

thus the screen is constantly maintained throughout and over the entireinside area of the flue of a uniform thickness and in condition toperform the work intended. A spraying of water from nozzles 9 ismaintained over the screen material, and these nozzles are shieldedwithin holes in the walls.

In orderto force the fine-dust and the metals or metalloids contained inthe gases to precipitate upon the first moving screemthe gases must bevery hot when they come into contact with it, and an abundant andcontinuous spraying of water over the entire surface of the screens mustbe maintained. The gases being veryhot, the evaporation will be rapid,

and to insure a successful precipitation of the metals or metalloidssuch rapid evaporation must be compensated for and the faces of thescreen must at all times be kept wet or at least moist.

As the quantity of matte or converter-slags at any smelting plant iscomparatively limited, the provision above described for passing suchmaterial repeatedly through the first screen is of practical value. Theadhering crust of flue-dust is so dense and hard that many layers of itmay be deposited upon the value-bearing screen material, and saidmaterial thus augmented to any extent desired.

The material after having been passed once or oftener through theapparatus may beremoved therefrom and treated in a blast-furnace orreverberatory furnace or in other suitablesmeltingorreducingapparatus.Such utilization of material containing metallic values for collectingthe flue-dust and enabling it to be returned to a smelting-furnace Iregard as broadly new.

The second, third, and fourth screens are intended to thoroughly arrestand to precipitate any remaining metals or metalloids in the fumes andto enable the ultimate discharge of these gases in harmless condition tothe atmosphere. The material from these screens after becoming foul maybe utilized as filling in underground mine-Workings, for which purposethe presence of the precipirated impurities is not objectionable. Toarrest and precipitate all the arsenic from the gases, it is necessaryto use an alkalinesolution or a dilute solution of sulfid of calcium onat least one of the filtering-screens, although a large proportion ofthe arsenic will be mechanically precipitated, together with the sulfur,iron, antimony, &c., by using water alone. Therefore on each screen Ispray either water or an alkaline solution or a weak solution of sulfidof calcium. At most points where copper-smelters are located alkaliwater is available almost without cost, and this ofiers at once a cheapand a most excellent precipitant for any arsenic contained in the fumes.

It should be understood that the essential feature of my presentinvention is the precipitation of the flue-dust upon screens ofvalue-bearing material fit for smelting or further treatment for thepurpose of recovering the dust and enriching the screen ma terial, andtherefore within the scope of my claims the subsequent screens may beomit ted or may be substituted by screening or filtering apparatus ofother kinds and made of other materials.

The apparatus may be modified in many ways, both in respect to the shapeof the screen-chamber and the nature and arrangement of the supports orholders for the screening material, since What I claim is 1. The methodherein described of recovering valuable dust from smelter-gases,whichconsists in precipitating the same upon filtering material such as ore,matte or con verterslag, containing metallic values fit for reduction orsmelting with the precipitated dust, whereby the values contained inboth the filtering material and the precipitated dust may be recoveredtogether, substantially as described.

2. The method herein described of recovering valuable dust fromsmelter-gases, which consists in precipitating the same upon wetfiltering material, such as ore, matte, or converterslag, containingmetallic values fit for reduction or smelting with the precipitateddust, whereby the values contained-in both the filtering material andthe precipitated dust may be recovered together; substantially asdescribed.

3. The method herein described of reco vering valuable dust fromsmelter-gases, which consists in precipitating the same upon filteringmaterial such as ore, matte, or converterslag, containing metallicvalues fit for reduction or smelting with the precipitated dust, wherebythe Values contained in both the filtering material and the precipitateddust may be recovered together, and subsequently smelting such materialwith the precipitated flue-dust; substantially as described.

In testimony whereof I have hereunto set my hand.

RALPH BAGGALEY. Witnesses:

THOMAS W. BAKEWELL, H. M. CORWIN.

